On Friday, December 30, 2022 9:02:56 AM EST Alessandro Vesely wrote:
> On Wed 28/Dec/2022 17:39:34 +0100 Scott Kitterman wrote:
> > On Wednesday, December 28, 2022 11:19:46 AM EST Alessandro Vesely wrote:
> >> Appendix A5 in the I-D describes "Issues with ADSP in Operation".  This
> >> appendix existed in RFC 7489 (March 2015), when ADSP was already set to
> >> Historic (November 2013).
> >> 
> >> Bullet #2 in that appendix says "Nonexistent subdomains are explicitly
> >> out
> >> of scope in ADSP."  DNARC, instead has an apposite np= policy.
> >> 
> >> However, in Authentication-Results one can write dkim-adsp=nxdomain.  I
> >> found no equivalent result for dmarc=.  Shouldn't there be one?
> > 
> > nxdomain isn't a DMARC result, so from that perspective, no.
> 
> Why not add it?  We'd write dmarc=temperror on a DNS hiccup, correct?  The
> result of DNS lookup strongly affects DMARC results.
> 
> It is important to know whether the From: domain exists.  The only standard
> way to report it is to write dkim-adsp=nxdomain, which is a nuisance.

I agree it strongly effects the DMARC results.  The difference is that 
temperror 
IS a DMARC result, nxdomain is not.

https://www.rfc-editor.org/rfc/rfc7489#page-43

> > I think a better question is should the A-R header field indicate which
> > tag was used for policy determination (p=, sp=, np=).  I think the answer
> > is, again, no.
> 
> The draft has a polrec.p= tag to report the policy found.  It is tricky to
> tweak that into, say, polrec.np=.  Would it mean that the polrec.domain had
> an np= tag, or that the receiver got nxdomain and hence determined to use
> an np= policy, irrespective of what was actually written in the policy
> record?
> > Is that currently captured in aggregate reporting?  If we're going to
> > indicate it anywhere, I think that's the right place.
> 
> I think having a strict match between A-R lines and aggregate reports would
> be a good thing.  To wit, one could debug emitted reports by looking at
> A-Rs.

I disagree with this as a goal.  Being able to fully reconstruct the 
authentication process was an explicit non-goal for A-R.  A-R communicates a 
result (thus the name).  If I see from an aggregate report that a policy was 
evaluated based on np= for a domain that I think should be p= or sp=, the 
answer lies in DNS, not email.

Scott K


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